Implement Raster.astype

[Copilot]

Raster lacked an astype method, forcing direct array mutation (raster.arr = raster.arr.astype("float32")) and breaking method chaining.

Changes

• Raster.astype(dtype) — new method returning a new Raster with the array cast to the given dtype; metadata is preserved unchanged. Follows the same copy-and-modify pattern as abs(), clamp(), etc.
• DTypeLike added to TYPE_CHECKING imports in raster.py
• TestAstype test class added covering dtype conversion, value preservation, and subclass return type

Usage

slope_raster = slope_raster.astype("float32")

# Or in a chain
result = raster.clamp(a_min=0).astype("float32")

Original prompt

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This section details on the original issue you should resolve

<issue_title>Implement Raster.astype</issue_title>
<issue_description>So we can do

slope_raster = slope_raster.astype("float32")

Instead of

slope_raster.arr = slope_raster.arr.astype("float32")

Useful for method chaining. Similar to to_crs and other cleanup methods</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes Implement Raster.astype #407

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[t-t-sonarqube]

Quality Gate passed

Issues

• 0 New Issues
• 0 Fixed Issues
• 0 Accepted Issues

Measures

• 0 Security Hotspots
• 100.00% Coverage (95.00% Estimated after merge)
• 0.00% Duplicated Code (0.00% Estimated after merge)

Project ID: tonkintaylor_rastr_c6820163-843b-45ef-9d15-db4bc95045e9

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